Turbulence muffle burner

ABSTRACT

The turbulence muffle burner is provided with a tubular member in surrounding relation to the burner to define at least two annular ducts. Air is directed through the ducts and directed into twisting paths within the ducts so that the velocity and the tangential velocity component of the air leaving the innermost duct are greater than the velocity and the tangential velocity component of the air leaving the outermost duct.

United States Patent Harendra Nath'Sharan Inventor Seuzach, Switzerland Appl. No. 880,683 Filed Nov. 28, 1969 Patented Oct. 12, 1971 Assignee Sulzer Brothers, Ltd.

Winterthur, Switzerland Priority Nov. 27, 1968 Switzerland 17646/68 TURBULENCE MUFFLE BURNER 9 Claims, 1 Drawing Fig.

US. Cl 431/183, 239/404 Int. Cl F23m 9/08 Field of Search 431/182,

[56] References Cited UNITED STATES PATENTS 2,757,721 8/1956 Reed et al 431/183 3,049,085 8/1962 Musat et al. 431/183 3,049,173 8/1962 Costello et al. 431/184 Primary ExaminerEdward G. Favors Attorney-Kenyon & Kenyon Reilly Carr & Chapin ABSTRACT: The turbulence muffle burner is provided with a tubular member in surrounding relation to the burner to define at least two annular ducts. Air is directed through the ducts and directed into twisting paths within the ducts so that the velocity and the tangential velocity component of the air leaving the innermost duct are greater than the velocity and the tangential velocity component of the air leaving the outermost duct.

TURBULENCE MUFFLEBURNER This invention relates to a turbulence muffle burner. More particularly, this invention relates to a turbulence muffle burner with a central oil or gas supply means.

Burners have been known which have been adjoined to a refractory muffle and have been constructed with a central means for supplying oil and/or gas and a means for supplying combustion air in which means are disposed to impart twist to the air flowing therethrough. Such burners have been employed, for example, for heating air intended for blast furnaces, for underwater combustion, for refuse combustion or for direct heating, for example, of induction furnaces during heating up. However, the thermal loadings referred to the muffle volume as well as the thermal loadings referred to the mufile cross section have been relatively small. As a result of such small loadings, these burners cannot be employed efficiently for steam-raising plants.

On the other hand, turbulence combustion chambers have also been known which are used in conjunction with steamraising plants and in which coal dust is burnt. In such combustion chambers, the combustion space has been surrounded by cooling tubes provided with a stamping mass. The stamping mass, on the one hand, enables the combustion temperature to be raised thus accelerating the combustion and, on the other hand, avoids quenching of the liquid slag when the slag touches the wall of the combustion chamber so that the slag can flow away. However, these known turbulence combustion chambers have also been unsuitable for achieving very high thermal loadings.

Accordingly, it is an object of the invention to provide turbulence muffle burners which are suitable for steam-raising plants.

It is another object of the invention to provide a muffle burner with a large output.

It is another object of the invention to provide a muffle burner with a thermal loading referred to the volume as well as the cross section which is three times as large as hitherto achieved values.

Briefly, the invention provides a turbulence muffle burner in which an air supply means mounted about a burner is divided into at least two annular ducts, for example, by a tubular member, each duct being provided with means for imparting twist such that over the entire load range, the velocity of the air leaving the annular duct nearest to the center is greater than the velocity of the air leaving the annular duct disposed distally relative to the center. Also, the means for imparting twist are so constructed that the tangential velocity component of the air discharged from the annular duct nearest to the center is greater than the tangential velocity component of the air discharged from the annular duct disposed distally relative to the center.

The dimensions of the turbulence muffle burner of the invention are substantially smaller than those of known burners. It is further possible with the burner to produce within the muffle a strong turbulence, similar to a potential turbulence, associated with an axial backflow formed along the longitudinal axis of the muffle. This results in an intensive and rapid mixing of fuel and combustion air so that the high temperature of the uncooled mufi'le wall produces a high combustion rate and therefore a high output density.

These and other objects and advantages of the invention will become apparent from the following detailed description and appended claims taken in conjunction with the accompanying drawings in which:

The FIGURE illustrates a horizontal section through a turbulence muffle burner according to the invention.

Referring to the drawing, the burner 1, has a cylindrical airdistribution box or chamber 2 tangentially adjoining a duct 3 through which combustion air is supplied to the burner l. A burner lance 4, supplied with fuel such as oil and/or gas via a pipeline 5, is disposed in the center of the distributor box 2 and has an end constructed as an atomizer nozzle 6. The lance 4 is mounted by means of a flange 7 on the end wall of the distributor box 2 and is guided in a bush 8 in the zone of the atomizer nozzle 6. In addition, the burner lance 4 is coaxially surrounded in the zone of the atomizer nozzle 6 by a tubular member 9 having an air entry end expanded in flared manner. The tubular member 9 in turn is surrounded by a tube 10 mounted via a conical wall 13 in the air-distribution box 2. One annular duct 40, 50 respectively is therefore formed between the tube 10 and the tubular member 9 on the one hand and between the tubular member 9 and the bush 8 on the other hand.

Means ll, 12 respectively are provided in each of the two annular ducts 40, 50 for imparting twist to the air flowing therethrough. For example, these means ll, 12 are formed by plates which are welded to the bush 8 and the tubular member 9 and to the tubular member 9 and the tube 10, respectively and formed into helical surfaces. The means 1 1, 12 are so constructed with respect to the ducts 40, 50 such that the tangential velocity component of the air discharged from the innermost annular duct 50 is greater than the tangential velocity component of the air discharged from the outermost annular duct 40.

The system thus formed for supplying combustion air is adjoined by a muffle 18 of ceramic material which initially opens in flared manner starting from the tube 10 and then continues in cylindrical section. The muffle 18 is guided with radial clearance in a plate jacket 16 joined to the conical wall 13. The end of the jacket 16 (disposed on the right in the drawing) is provided with a flange 17 by means of which the burner l is mounted on the wall 19 of the steam generator (not shown in detail). The wall 19 of the steam generator is provided with an aperture having the external diameter of the mufl'le 18 so that the flame gases discharged from the burner 1 can flow without obstruction into the steam generator so as to give up heat to tubes 20 through which working medium flows.

The conical wall 13 within the distribution box 2 is stiffened by radial ribs 14 which also serve for securing the tube 10 in place. The tube 10 is also surrounded by a sleeve 15 which is adjustable in the axial direction and by means of which it is possible to vary the entry flow cross section of the annular duct 40 disposed distally relative to the center of the burner to enable the air supply to the burner l to be adapted to the varying load of the steam generator.

During operation of the burner l, the combustion air is discharged from the pipeline 3 at moderate velocity and tangentially into the distribution chamber 2 and an approximately constant proportion of the air flows into the annular duct 50 surrounded by the tubular member 9. The twist plates l1 impart twist to this proportion of air whereupon the air is discharged in turbulence form from the duct 50 and mixes intensively with the fuel oil and/or gas atomized in the atomizer nozzle 6. The remaining air supplied to the distribution chamber 2 flows into the annular duct 40 bounded by the tubular member 9 and the tube 10, where twist is also imparted on the air by the plates 12. The twist of the air in the annular duct 40 is in the same sense as the twist of the air in the annular duct 50 which is nearest to the burner axis or center. The flared construction of the tubular member 9 functions as a means for maintaining the velocity of the air discharged from the innermost duct 50 substantially constant while also ensuring that the velocity of the air discharged from the outermost annular duct 40 is always somewhat less than the velocity of the air discharged from the innermost annular duct 50, even if the adjustable sleeve 15 is displaced completely to the right as viewed in the drawing so that the entry cross section of the outermost annular duct 40 is the largest.

in addition to the velocity difference, due to the shape of the twist plates ll, 12 a difference occurs between the tangential velocity components of the air discharged from the innermost annular duct 50 and the air discharged from the outermost annular duct 40 in such a manner that the component of the innermost airflow is greater than that of the outermost airflow. Accordingly, a potential turbulence velocity distribution is produced at the entry of the muffle 18 resulting in a gas backflow in the center of the muffle as indicated in diagrammatic form by the arrows in the drawing. The direction of these arrows represents, in the most general form, the axial components of different streamlines, as turned back into the drawing plane. The actual flow is characterized by a twist superimposed on the drawn lines and resulting in a quasi winding up of the flame within the mufile so that combustion is completed within the short muffle volume. This special guiding of the combustion air ensures an intensification of the combustion process.

By adjusting the sleeve 15 in the drawing to the left, as would be done if the steam generator load diminishes, the velocity of the air discharged from the outermost annular duct 40 is reduced while the velocity of the air discharged from the innermost annular duct 50 remains substantially constant. Accordingly, the above-described effect is maintained even if the steam generator load changes while at the same time the combustion oil is always properly atomized.

According to another embodiment of the invention, two tubular members for subdividing the air supply may be provided in place of one tubular member 9, so that three annular ducts are formed.

The invention thus provides a turbulence muffle burner which can be of substantially small size while of substantially large output. For example, the diameter of the outermost annular duct 40 can amount to 0.3 to 0.6 times the internal diameter of the muffle 18 while the length of the muffle l8 amounts to 0.5 to 2 times the internal diameter of the muffle 18. Also, the exit cross sections of the ducts 40, 50 are of approximately equal size.

What is claimed is:

l. A turbulence muffle burner comprising central means for supplying fuel;

means for supplying combustion air surrounding said central means, said means including at least one tubular member about said central means dividing said means into at least two annular ducts to cause the velocity of the air discharged from the innermost of said ducts to be greater than the velocity of the air discharged from the outermost of said ducts;

means in each said duct for imparting twist to the air flowing through each said duct to cause the tangential velocity component of the air discharged from said innermost duct to be greater than the tangential velocity component of the air discharged from said outermost duct over the entire load range; and

a refractory muffle adjoining said ducts to receive the twisted air flows.

2. A turbulence muffle burner as set forth in claim 1 wherein said tubular member has a flared air entry end.

3. A turbulence muffle burner as set forth in claim 1 further comprising means for maintaining the velocity of the air discharged from said innermost duct substantially constant.

4. A turbulence muffle burner as set forth in claim 1 further comprising means for varying the flow cross section of said outermost duct.

5. A turbulence muffle burner as set forth in claim 4 wherein said means for varying the flow cross section of said outermost duct comprise an axially adjustable sleeve.

6. A turbulence muffle burner as set forth in claim 1 wherein the diameter of said outermost duct amounts to 0.3 to 0.6 times the internal diameter of said muffle and the length of said muffle amounts to 0.5 to 2 times the internal diameter of said muffle.

7. A turbulence muffle burner as set forth in claim 1 wherein the exit cross section of said annular ducts are approximately of equal size.

8. A turbulence muffle burner as set forth in claim 1 wherein the imparting means in all annular ducts are directed in the same sense.

9. A turbulence muffle burner as set forth in claim I wherein each means for imparting twist to the air is disposed to impart a twist of the same sense of direction in each duct. 

1. A turbulence muffle burner comprising central means for supplying fuel; means for supplying combustion air surrounding said central means, said means including at least one tubular member about said central means dividing said means into at least two annular ducts to cause the velocity of the air discharged from the innermost of said ducts to be greater than the velocity of the air discharged from the outermost of said ducts; means in each said duct for imparting twist to the air flowing through each said duct to cause the tangential velocity component of the air discharged from said innermost duct to be greater than the tangential velocity component of the air discharged from said outermost duct over the entire load range; and a refractory muffle adjoining said ducts to receive the twisted air flows.
 2. A turbulence muffle burner as set forth in claim 1 wherein said tubular member has a flared air entry end.
 3. A turbulence muffle burner as set fortH in claim 1 further comprising means for maintaining the velocity of the air discharged from said innermost duct substantially constant.
 4. A turbulence muffle burner as set forth in claim 1 further comprising means for varying the flow cross section of said outermost duct.
 5. A turbulence muffle burner as set forth in claim 4 wherein said means for varying the flow cross section of said outermost duct comprise an axially adjustable sleeve.
 6. A turbulence muffle burner as set forth in claim 1 wherein the diameter of said outermost duct amounts to 0.3 to 0.6 times the internal diameter of said muffle and the length of said muffle amounts to 0.5 to 2 times the internal diameter of said muffle.
 7. A turbulence muffle burner as set forth in claim 1 wherein the exit cross section of said annular ducts are approximately of equal size.
 8. A turbulence muffle burner as set forth in claim 1 wherein the imparting means in all annular ducts are directed in the same sense.
 9. A turbulence muffle burner as set forth in claim 1 wherein each means for imparting twist to the air is disposed to impart a twist of the same sense of direction in each duct. 